On Wednesday afternoon, the Bitcoin bubble appears to have burst. As of this writing, its current value is around $160—down from a high of $260. (It fell as low as $130 today.) There is no obvious explanation for why the digital currency has fallen so far and so fast, although the market correcting after such a huge rise might be a good explanation. (Update 4:05pm CT: Bitcoin seems to have somewhat recovered and appears to be hovering around $200. Update 6:00pm CT: The exchange rate has fallen back to around $160.)